ERP121201 PRJEB37861 ena-STUDY-LEIDEN UNIVERSITY MEDICAL CENTER-17-04-2020-07:29:16:566-445 Periodic screening of donor faeces with a quarantine period to prevent transmission of Multidrug Resistant Organisms during Faecal Microbiota Transplantation: an observational cohort study Background: In 2019, an FDA warning was issued after transfer of faeces containing an extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli by faecal microbiota transplantation (FMT), which led to bacteraemia in two immunocompromised patients. Consequently, we evaluated the faeces donor screening protocol of the Netherlands Donor Faeces Bank (NDFB), consisting of periodic screening of multi-drug resistant organisms (MDRO) every three months combined with additional screening on indication (e.g. after foreign country visits) and application of a quarantine period. Methods: A retrospective cohort study was performed. Data collected between November 2015 and October 2019 on MDRO testing results of faeces from tested individuals were analysed. Furthermore, previously quarantined faecal suspensions approved for FMT-treatment between January 2017 and April 2019 were tested for the presence of MDRO using aselective broth enrichment media. Whole-genome sequencing with core-genome MultiLocus Sequence Typing (cgMLST) was performed on all MDRO isolates. Findings: Among initial screenings, six of 66 tested individuals were MDRO-positive (9%). Of 16 active donors, four (25%) became MDRO-positive at some timepoint during donation activities, with a median donation duration of 268 days. An ESBL-producing E. coli was found in 14 of 19 (74%) detected MDRO among all screening results. Of 170 approved faecal suspensions, none contained an MDRO (95% CI 0:2). Furthermore, cgMLST revealed that all MDRO were genetically different. Interpretation: Healthy faeces donors are at risk to become colonised with MDRO at some point during donation activities. Our current screening protocol did not result in approval of MDRO-positive faecal suspensions for FMT-treatment. Funding: The NDFB received unrestricted grants from Vedanta Biosciences. Background: In 2019, an FDA warning was issued after transfer of faeces containing an extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli by faecal microbiota transplantation (FMT), which led to bacteraemia in two immunocompromised patients. Consequently, we evaluated the faeces donor screening protocol of the Netherlands Donor Faeces Bank (NDFB), consisting of periodic screening of multi-drug resistant organisms (MDRO) every three months combined with additional screening on indication (e.g. after foreign country visits) and application of a quarantine period. Methods: A retrospective cohort study was performed. Data collected between November 2015 and October 2019 on MDRO testing results of faeces from tested individuals were analysed. Furthermore, previously quarantined faecal suspensions approved for FMT-treatment between January 2017 and April 2019 were tested for the presence of MDRO using aselective broth enrichment media. Whole-genome sequencing with core-genome MultiLocus Sequence Typing (cgMLST) was performed on all MDRO isolates. Findings: Among initial screenings, six of 66 tested individuals were MDRO-positive (9%). Of 16 active donors, four (25%) became MDRO-positive at some timepoint during donation activities, with a median donation duration of 268 days. An ESBL-producing E. coli was found in 14 of 19 (74%) detected MDRO among all screening results. Of 170 approved faecal suspensions, none contained an MDRO (95% CI 0:2). Furthermore, cgMLST revealed that all MDRO were genetically different. Interpretation: Healthy faeces donors are at risk to become colonised with MDRO at some point during donation activities. Our current screening protocol did not result in approval of MDRO-positive faecal suspensions for FMT-treatment. Funding: The NDFB received unrestricted grants from Vedanta Biosciences. ENA-FIRST-PUBLIC 2020-04-24 ENA-LAST-UPDATE 2020-04-23